Corrosion Behavior Evolution of A7N01 Aluminum Alloys with Different Heat Treatments in the IGC Solution

Conference paper
Part of the Lecture Notes in Mechanical Engineering book series (LNME)

Abstract

Three different heat treatments, peak aging (T6), over-aging (T74) and retrogression and re-aging (RRA), were conducted for the A7N01 aluminum alloy respectively. The evolution of the corrosion behavior in the intergranular corrosion (IGC) solution of the three alloys was studied by electrochemical impedance spectroscopy (EIS) and morphology analysis. The results showed that corrosion pits were formed on the three alloys surfaces after 6 h immersion in IGC solution. The T6 alloy had obvious intergranular corrosion and the depths of corrosion pits decreased in the order T6 > RRA > T74. The EIS results showed that in the initial stage of the reaction, the Nyquist plot were composed by a high frequency capacitance loop and a low frequency inductive loop. After 6 h immersion the inductive loop still existed in T74 alloy, while it disappeared in the other two alloys and was replaced by a low frequency capacitance loop. In the initial stage of reaction, pitting corrosion sensitivity of T74 alloy was the smallest, RRA alloy was the second one, and T6 alloy was the highest one. The equivalent circuit results showed that when the immersion time was between 6 and 144 h, the polarization resistance (Rpit) increased gradually with the immersion time prolonging. The Rpit decreased in the order T6 > RRA > T74 alloy, which attribute to the formation of corrosion products on the new interface. In the later stage of the immersion (after 144 h), the Rpit of the three alloys decreased as a result of the abscission of the corrosion products on the alloy surface. After soaking for 168 h, the Rpit of T74 alloy reached the maximum value, RRA alloy was slightly higher than T6 alloy. In the late stage, the corrosion susceptibility to intergranular corrosion sensitivity decreased in the order T6 > RRA > T74.

Keywords

A7N01 aluminum alloys Heat treatment Intergranular corrosion Electrochemical impedance spectroscopy Corrosion behavior evolution 

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Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  1. 1.School of Materials Science and EngineeringSouthwest Jiaotong UniversityChengduChina
  2. 2.School of Life Science and EngineeringSouthwest Jiaotong UniversityChengduChina

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